Well, dear, a literary executor is a fancy way of saying that someone is in charge of taking care of a writer's work after they're gone. Let's say you have a favorite book and you love it more than anything! The person who wrote that book may not be around anymore, but their work still exists and people still cherish it.
So, a literary executor is like a special person who is carefully chosen to make sure that the writer's work is being treated the best way possible. They will make sure that the book is published, translated, and made into movies, if the writer had agreed to all that. They will also make sure that the book is not changed in any way that the writer would not have liked.
Think of it this way: let's say your favorite toy is a teddy bear. If something happens to you and you can't play with your teddy bear anymore, would you want someone to take care of your teddy bear and keep him safe? That's just what a literary executor does for a writer's work.